A processing apparatus, for example, an etching apparatus includes a processing container structured in an airtight manner and a holding body arranged in the processing container to hold a substrate to be processed and further produces a plasma to apply a designated processing on the substrate. When the processing on the substrate is continued, the interior of the processing container may be contaminated by by-products etc. or internal components may be wasted. Therefore, it is performed to stop the operation of the processing apparatus once and further carry out maintenance, such as cleaning of the interior of the processing apparatus and exchanging of consumable parts. After completion of the maintenance, the processing apparatus is restarted.
For example, in case of an etching apparatus, when restarting the operation, it is carried out to supply an interior of the apparatus with a designated number of dummy wafers and further repeat an etching cycle thereon, performing so-called “seasoning” in order to regularize an interior of the apparatus as required at the production. After completion of the seasoning, etching rate, in-plane uniformity of etching, etc. are examined. Here performed is a data analysis using a measured data obtained by the plural dummy wafers at seasoning, for example, data analysis using a measured data of emission spectrum obtained by an end-point detector. Then, a judgment whether the seasoning has been completed is accomplished by reviewing the change of such an analyzed date.
In the conventional analyzed data, however, it is remarkably difficult to find out whether a change providing a judgmental standard for completion of seasoning comes from a change due to the seasoning, in other words, the change based on a change of the state in the processing container or comes from another change based on a change in temperature among the respective dummy wafers.
That is, although the inventors have analyzed the measured data by use of a principal component analysis as being one multivariate analysis as described later, the analysis results in that there are recognized two great peaks each exhibiting changes, thereby making it difficult to judge whether the seasoning has been completed or not. Now, we describe this principal component analysis. In this case, the measured data has been picked as per usual. For instance, it was carried out on the first day to load one hundred and thirty (130) dummy wafers and subsequently carried out on the second day to load thirty (30) dummy wafers for etching under the flow of production. As a result of applying principal component analysis on the measured data of emission spectrum of the 51st. to 60th. dummy wafers and the 121st. to 130th. dummy wafers on the first day, we obtained analytic results as shown in FIGS. 8A, 8B and FIGS. 9A, 9B. In this principal component analysis, by use of 297 sorts of wavelengths in the short-wavelength range from 193 nm to 419 nm, it is carried out to measure the intensities of the respective wavelengths for eighteen (18) times every three seconds in one minute per one dummy wafer and furthermore, the principal component analysis is applied on the so-obtained measured data. Then, the scores of principal components and the residual errors at the respective measurements are calculated respectively. By plotting HOTELLINGS TSQUARE (square sums of the scores of the principal components), we obtained FIGS. 8A and 9A. Further, by plotting the square sums of the residual errors (residual scores), we obtained FIGS. 8B and 9B. As obvious from these analytic results, FIGS. 3A and 3B, these are recognized great peaks on the first day and also the second day in each graph thereby making it difficult to judge the completion of seasoning. It is noted that the horizontal axis of each graph denotes the number of measurements.
In order to solve the above problem, an object of the present invention is to provide a plasma processing method, a detecting method of the completion of seasoning, a plasma processing apparatus and a storage medium, all that make it possible to judge the completion of seasoning definitely.
As a result of the inventors' studying on the reason of two peaks recognized, it is found that such an appearance of two peaks is attributable to the picking method of measured data used for the data-analysis. Consequently, we obtain a knowledge that the application of a specified process on a processing container in picking data would allow a change due to the seasoning to be grasped certainly while eliminating an influence due to temperature change among the dummy wafers, whereby the completion of seasoning can be judged absolutely.